Introduce github action linting in pre-commit

[kwk]

This checks github action files in pre-commit. To run this locally, make sure you have shellcheck installed.

actionlint found these kind of problems and this PR addresses them ($ actionlint -oneline).

1. Use $(...) notation instead of legacy backticks `...`
2. Double quote to prevent globbing and word splitting
3. Don't use variables in the printf format string. Use printf '..%s..' "$foo"
4. Use -n instead of ! -z
5. Consider using { cmd1; cmd2; } >> file instead of individual redirects
6. "github.event.comment.body" is potentially untrusted. avoid using it directly in inline scripts. instead, pass it through an environment variable. see https://docs.github.com/en/actions/security-for-github-actions/security-guides/security-hardening-for-github-actions for more details
7. This expression is constant. Did you forget a $ somewhere? - I have ignored that one because I think it was a false report. Wasn't it?

Here's a detailed list of all the problems that actionlint found:

.github/workflows/build-reproducer-container.yml:22:9: shellcheck reported issue in this script: SC2086:info:3:25: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/build-reproducer-container.yml:22:9: shellcheck reported issue in this script: SC2086:info:4:40: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/build-reproducer-container.yml:22:9: shellcheck reported issue in this script: SC2086:info:5:21: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/check-snapshots.yml:61:9: shellcheck reported issue in this script: SC2059:info:2:8: Don't use variables in the printf format string. Use printf '..%s..' "$foo" [shellcheck]
.github/workflows/check-snapshots.yml:83:9: shellcheck reported issue in this script: SC2236:style:3:7: Use -n instead of ! -z [shellcheck]
.github/workflows/check-snapshots.yml:83:9: shellcheck reported issue in this script: SC2006:style:10:12: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/check-snapshots.yml:83:9: shellcheck reported issue in this script: SC2086:info:14:17: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/check-snapshots.yml:83:9: shellcheck reported issue in this script: SC2086:info:16:9: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/check-snapshots.yml:83:9: shellcheck reported issue in this script: SC2086:info:23:14: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:49:9: shellcheck reported issue in this script: SC2059:info:2:8: Don't use variables in the printf format string. Use printf '..%s..' "$foo" [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2236:style:2:4: Use -n instead of ! -z [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2006:style:4:7: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2006:style:5:11: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2006:style:7:11: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2006:style:8:10: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2129:style:11:1: Consider using { cmd1; cmd2; } >> file instead of individual redirects [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2086:info:11:30: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2086:info:12:30: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2086:info:13:28: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2086:info:14:36: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2086:info:15:112: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2086:info:16:120: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:61:9: shellcheck reported issue in this script: SC2086:info:17:60: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:82:9: shellcheck reported issue in this script: SC2236:style:2:4: Use -n instead of ! -z [shellcheck]
.github/workflows/fedora-copr-build.yml:82:9: shellcheck reported issue in this script: SC2006:style:5:27: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:82:9: shellcheck reported issue in this script: SC2129:style:12:1: Consider using { cmd1; cmd2; } >> file instead of individual redirects [shellcheck]
.github/workflows/fedora-copr-build.yml:82:9: shellcheck reported issue in this script: SC2006:style:12:29: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:82:9: shellcheck reported issue in this script: SC2086:info:12:75: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:82:9: shellcheck reported issue in this script: SC2086:info:13:64: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:82:9: shellcheck reported issue in this script: SC2006:style:14:29: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:82:9: shellcheck reported issue in this script: SC2086:info:14:76: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:101:9: shellcheck reported issue in this script: SC2236:style:2:4: Use -n instead of ! -z [shellcheck]
.github/workflows/fedora-copr-build.yml:101:9: shellcheck reported issue in this script: SC2006:style:5:17: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:101:9: shellcheck reported issue in this script: SC2086:info:7:15: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:101:9: shellcheck reported issue in this script: SC2086:info:12:20: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:119:9: shellcheck reported issue in this script: SC2236:style:2:4: Use -n instead of ! -z [shellcheck]
.github/workflows/fedora-copr-build.yml:127:9: shellcheck reported issue in this script: SC2236:style:2:4: Use -n instead of ! -z [shellcheck]
.github/workflows/fedora-copr-build.yml:127:9: shellcheck reported issue in this script: SC2006:style:4:13: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:127:9: shellcheck reported issue in this script: SC2006:style:7:19: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:127:9: shellcheck reported issue in this script: SC2006:style:8:19: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:127:9: shellcheck reported issue in this script: SC2086:info:16:3: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:147:9: shellcheck reported issue in this script: SC2236:style:2:4: Use -n instead of ! -z [shellcheck]
.github/workflows/fedora-copr-build.yml:163:9: shellcheck reported issue in this script: SC2236:style:2:4: Use -n instead of ! -z [shellcheck]
.github/workflows/fedora-copr-build.yml:163:9: shellcheck reported issue in this script: SC2006:style:5:13: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/fedora-copr-build.yml:163:9: shellcheck reported issue in this script: SC2086:info:7:17: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:181:9: shellcheck reported issue in this script: SC2236:style:2:4: Use -n instead of ! -z [shellcheck]
.github/workflows/fedora-copr-build.yml:181:9: shellcheck reported issue in this script: SC2086:info:14:21: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/fedora-copr-build.yml:181:9: shellcheck reported issue in this script: SC2006:style:19:40: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/mass-rebuild-reporter.yml:52:9: shellcheck reported issue in this script: SC2086:info:3:29: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/mass-rebuild-reporter.yml:52:9: shellcheck reported issue in this script: SC2086:info:12:6: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/mass-rebuild-reporter.yml:52:9: shellcheck reported issue in this script: SC2086:info:12:24: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/mass-rebuild-reporter.yml:52:9: shellcheck reported issue in this script: SC2086:info:13:29: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/mass-rebuild-reporter.yml:52:9: shellcheck reported issue in this script: SC2086:info:15:28: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/mass-rebuild-reporter.yml:73:9: shellcheck reported issue in this script: SC2086:info:2:42: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/mass-rebuild-runner.yml:30:9: shellcheck reported issue in this script: SC2059:info:2:8: Don't use variables in the printf format string. Use printf '..%s..' "$foo" [shellcheck]
.github/workflows/retest.yml:71:24: "github.event.comment.body" is potentially untrusted. avoid using it directly in inline scripts. instead, pass it through an environment variable. see https://docs.github.com/en/actions/security-for-github-actions/security-guides/security-hardening-for-github-actions for more details [expression]
.github/workflows/retest.yml:82:9: shellcheck reported issue in this script: SC2086:info:2:17: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/sync-on-llvm-version.yml:62:9: shellcheck reported issue in this script: SC2006:style:12:15: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/sync-on-llvm-version.yml:62:9: shellcheck reported issue in this script: SC2086:info:20:38: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/sync-on-llvm-version.yml:62:9: shellcheck reported issue in this script: SC2086:info:26:28: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/sync-on-llvm-version.yml:62:9: shellcheck reported issue in this script: SC2006:style:32:23: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/sync-on-llvm-version.yml:62:9: shellcheck reported issue in this script: SC2086:info:34:48: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/sync-on-llvm-version.yml:62:9: shellcheck reported issue in this script: SC2086:info:35:58: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/sync-on-llvm-version.yml:62:9: shellcheck reported issue in this script: SC2006:style:37:20: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/sync-on-llvm-version.yml:62:9: shellcheck reported issue in this script: SC2086:info:37:38: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/sync-on-llvm-version.yml:62:9: shellcheck reported issue in this script: SC2006:style:38:25: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/sync-on-llvm-version.yml:62:9: shellcheck reported issue in this script: SC2086:info:38:48: Double quote to prevent globbing and word splitting [shellcheck]
.github/workflows/update-build-time-diagrams.yml:37:9: shellcheck reported issue in this script: SC2059:info:2:8: Don't use variables in the printf format string. Use printf '..%s..' "$foo" [shellcheck]
.github/workflows/update-build-time-diagrams.yml:65:9: shellcheck reported issue in this script: SC2046:warning:2:79: Quote this to prevent word splitting [shellcheck]
.github/workflows/update-build-time-diagrams.yml:65:9: shellcheck reported issue in this script: SC2006:style:2:79: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/update-build-time-diagrams.yml:65:9: shellcheck reported issue in this script: SC2046:warning:3:79: Quote this to prevent word splitting [shellcheck]
.github/workflows/update-build-time-diagrams.yml:65:9: shellcheck reported issue in this script: SC2006:style:3:79: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/update-build-time-diagrams.yml:65:9: shellcheck reported issue in this script: SC2046:warning:4:73: Quote this to prevent word splitting [shellcheck]
.github/workflows/update-build-time-diagrams.yml:65:9: shellcheck reported issue in this script: SC2006:style:4:73: Use $(...) notation instead of legacy backticks `...` [shellcheck]
.github/workflows/update-build-time-diagrams.yml:65:9: shellcheck reported issue in this script: SC2078:error:13:7: This expression is constant. Did you forget a $ somewhere? [shellcheck]
.github/workflows/update-build-time-diagrams.yml:65:9: shellcheck reported issue in this script: SC2078:error:13:31: This expression is constant. Did you forget a $ somewhere? [shellcheck]

[nikic]

LGTM